Hi-rail capability refers to railway wheels, usually retractable, that are attached to standard roadway vehicles for the purpose of allowing the vehicles to travel on conventional railroad tracks in addition to conventional roadways. Hi-rail vehicles are commonly used as maintenance vehicles or as track inspection cars due to their mobility on both standard highways and railroad tracks.
A conventional hi-rail vehicle is described in U.S. Pat. No. 4,583,465 issued to Power, Sr. This design illustrates a railway wheel apparatus that allows simultaneous actuation of two cylinders to lower the railway wheel apparatus onto the railroad track. In operation, the railway wheels contact the rails and raise at least a portion of the vehicle off of the railroad track. Generally, the rear pair of vehicle wheels remain in contact with the railroad track to be able to propel the vehicle on the railroad tracks. A problem with this design is that the vehicle tires remain in constant contact with the railroad track, and subsequently will lose traction due to wear of the tire. Because the railway wheel apparatus remains at a constant position with respect to the railroad track, the wear of the vehicle tires will cause the traction between the vehicle tires and the railroad track to decrease. Consequently, in order to regain the traction lost due to wear of the vehicle tires, either the hi-rail wheel assembly must be adjusted through technical and complex mechanical adjustments of the wheels that reposition the vehicle at a lower level, which can be very complicated and require great effort, or the worn vehicle wheels will have to be replaced on the vehicle by new wheels that have not experienced the deterioration of the use, thereby discarding the worn wheels before the end of the standard life of the wheels.
What is needed, then, and not found in the prior art, is a hi-rail assembly that provides a means for making adjustments to reduce the distance between the hi-rail assembly and railroad tracks so that the vehicle tires will continue to make a satisfactory connection with the railroad tracks.